The question of uniformity in skeletal age changes across populations is fundamental to all comparative work in skeletal biology. Whether an aging standard will work on target groups that differ in time, space, and background from the reference sample is essential for reliable, accurate age estimation. This research addressed whether a difference in skeletal senescence exists between older American documented collections and more recent ones. The pubic symphysis, auricular surface, sternal rib end, and suture obliteration were scored for a sample of American Blacks and Whites drawn from the Terry, Hamann-Todd, Bass Documented, Maxwell Museum, and Maricopa County Forensic Science Center collections. The samples were divided into two groups: the Reference group included the Terry and Hamann-Todd samples, and the Recent group included the remaining three series. Differences between Reference and Recent groups were tested using proportional odds probit regression analysis and an analysis of deviance.
Results indicated a significant difference in pubic symphyseal senescence between older Reference and more Recent American skeletal samples. No difference was found for cranial suture closure or the sternal rib end. Statistical problems and noteworthy critiques of auricular surface aging methods precluded an assessment of whether a difference between groups was present for this indicator. For the pubic symphysis, a slight deceleration of the rate of metamorphosis was reported for the Recent group, particularly for males and Whites. However, the broad age ranges associated with phases defined by most pubic symphyseal aging methods appear to mitigate this problem for forensic assessments of age at death. In contrast, paleodemographic and bioarchaeological analyses may be more greatly affected, as broad age ranges are often not desirable for such investigations.
These results advance anthropologists’ current knowledge and understanding of the applicability and reliability of aging standards when used on skeletal samples differing in time, space, and composition from the reference sample, and impact how skeletal age estimations are interpreted in forensic anthropological, paleodemographic, and bioarchaeological investigations. Uncertainty as to the possible causes for the differences observed, whether due to secular change, sampling issues, observer bias, or environmental factors, provides an abundance of future research opportunities.